1. Field of the Invention
The present invention relates to a wet-type image forming apparatus. More particularly, the present invention relates to a wet-type image forming apparatus, a method for sensing the concentration of a toner, and a method for controlling the wet-type image forming apparatus.
2. Description of the Related Art
Generally, image forming apparatuses are divided into monochromatic image forming apparatuses and color image forming apparatuses. Monochromatic image forming apparatuses form images in black and white by using only a one-color developer, while color image forming apparatuses form colorful images by using developers of various colors such as magenta, cyan, yellow, and black.
As well known to those skilled in the art, an electrophotographic image forming apparatus forms an electrostatic latent image on an organic photoconductor that is charged by a charging unit to a predetermined potential with a laser beam emitted from a laser scanning unit. The electrostatic latent image is developed with a developer and transferred into a visible image on paper. In a color image forming apparatus, the organic photoconductor of each color is developed with developers of each color, and then the developed images are overlapped and transferred to an intermediate transfer medium such as an intermediate transfer belt (ITB). A color image obtained by overlapping images of each color on the intermediate transfer medium is then transferred onto printing paper. The printing paper containing the color image goes through a series of fixing processes and is then ejected out of the image forming apparatus.
Herein, the developer is comprised of ink prepared by mixing a powder-type toner having a predetermined color, and a liquid carrier. The developer is accommodated in and supplied from a separate developer cartridge which is mounted on the image forming apparatus. The developer contained in the developer cartridge is maintained to have a predetermined reference concentration of toner with respect to carrier, and which is set in the image forming apparatus. However, the concentration of the toner can be outside of the reference concentration value while the developer is consumed due to a printing environment factor and/or an error in data. In this case, it is hard to acquire an image of a desired color and concentration.
Accordingly, a system and method is needed to sense and maintain the concentration of the toner in the cartridges at a uniform level.